nginx + keepalived 安装配置高可用+负载均衡

以两台服务器节点为例,无特殊说明两个节点均需要安装配置

1. 安装配置nginx

1.1 安装nginx环境所需依赖

yum -y install gcc zlib zlib-devel pcre-devel openssl openssl-devel

1.2 下载并解压nginx安装包。官方下载地址

wget http://nginx.org/download/nginx-1.13.7.tar.gz
tar -xvf nginx-1.13.7.tar.gz

1.3 安装nginx

# 进入nginx目录执行命令
cd nginx-1.13.7
./configure
make && make install

1.4 配置nginx软连接

ln -s /usr/local/nginx/sbin/nginx /usr/local/bin/nginx

1.5 设置nginx环境变量

vi /etc/profile

PATH=$PATH:/usr/local/nginx/sbin
export PATH


source /etc/profile

1.6 设置nginx自启

vi /lib/systemd/system/nginx.service
#加入以下代码
[Unit]
Description=nginx
After=network.target

[Service]
Type=forking
ExecStart=/usr/local/nginx/sbin/nginx
ExecReload=/usr/local/nginx/sbin/nginx -s reload
ExecStop=/usr/local/nginx/sbin/nginx -s quit
PrivateTmp=true

[Install]
WantedBy=multi-user.target


#使生效
systemctl enable nginx.service

1.7 配置nginx负载

# 例如有两个服务， 地址分别是 n1.bigdatatest.com,n2.bigdatatest.com
cd /usr/local/nginx/

vi conf/nginx.conf


# 例如有两个服务， 地址分别是 n1.bigdatatest.com,n2.bigdatatest.com
cd /usr/local/nginx/

vi conf/nginx.conf


    upstream kylinTest {
      server n1.bigdatatest.com;
      server n2.bigdatatest.com;
      ip_hash;
    }   

server {
        listen       81;
        server_name  localhost;

        location / {
            proxy_pass http://kylinTest;
            proxy_set_header Host $http_host;
            proxy_cookie_path / /;
            proxy_cookie_domain  http://kylinTest 127.0.0.1:81;
        }


        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

    }

1.8 启动

systemctl start nginx

2. 安装配置keepalived

参考文章Keepalived 搭建 Nginx 集群(主从模式)
2.1 安装

yum install keepalived -y

2.2 修改配置文件，默认在/etc/keepalived/keepalived.conf
注意： 检测脚本一定要写在vrrp_instance的前面，括号前后要有空格，trace_script要写在vip的后面

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {  # 异常邮件通知
     acassen@firewall.loc # 收件人邮箱
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc # 配置发件人邮箱
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
   vrrp_skip_check_adv_addr
   # vrrp_strict # 注释掉严格模式
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_script chk_haproxy {
    script "/etc/keepalived/chk_nginx.sh" # keepalived 监测 nginx 的监本路径和名称
    interval 2
    weight 2
}


vrrp_instance VI_1 {
    state MASTER # 服务器状态,MASTER 代表主服务器, BACKUP 是备份服务器
    interface eth0 # 通信端口,通过 ifconfig 命令可以看到,根据自己的机器配置
    virtual_router_id 190 # 虚拟路由 ID ,主实例和副本实例保持一致
    priority 100 # 权重比,主服务器的 priority 比副本服务器大即可
    advert_int 1 # 心跳间隔,单位秒, keepalived 多机器集群通过心跳检测,如果发送心跳没反应,就立刻接管
    authentication { # 服务器之间的通信密码
        auth_type PASS
        auth_pass 1111
    }
    
    virtual_ipaddress { # 自定义虚拟 ip ,可以配置多个,每行一个
        172.20.11.190
    }
    
    track_script { # keepalived 的监测脚本,与 vrrp_script 定义的名称一致
      chk_haproxy
    }
}

2.3 编写验证脚本

vi /etc/keepalived/chk_nginx.sh

#!/bin/bash
# nginx 挂掉之后, keepalived 重新启动 nginx ,若不能启动 则关闭当前 keepalived
status=`ps -ef|grep -w  nginx|grep -v grep|wc -l`
echo ${status}
if [ ${status} -eq 0 ]; then
    systemctl start nginx.service
    sleep 2
    status2=`ps -ef|grep -w  nginx|grep -v grep|wc -l`
    echo ${status2}
    if [ ${status2} -eq 0  ]; then
            systemctl stop keepalived.service
    fi
fi

注：如果开启了防火墙可能出现两台都出现VIP现象，需要开启vrrp协议

# 如果防火墙是firewall
firewall-cmd --direct --permanent --add-rule ipv4 filter INPUT 0  --protocol vrrp -j ACCEPT
firewall-cmd --reload
# 如果是iptables，主节点上运行命令时就写副节点IP，副节点运行命令时就写主节点IP
-A INPUT -i em1 -p vrrp -s [其他节点的IP]  -j ACCEPT

2.4 启动

systemctl start keepalived

# 设置开机自启
systemctl enable keepalived

2.5 测试
当两台正常启动时，通过ip a命令查看， VIP应该在主的上，即节点1


当把节点1的nginx关闭，节点一的Keepalived会自动启动nginx。只有当nginx无法被自动拉起时，keepalived才会自动关闭

这里直接停止keepalived，VIP将指向备机
systemctl stop keepalived

这时 VIP在节点2上

当把节点1的keepalived启动时，VIP将重新被节点1接管
systemctl start keepalived